Mars varies in temperature hugely between night and day. On the slopes where indirect evidence of flowing water was discovered, the temperature is between 0 C and -23 C when they start to flow. The surface can get quite hot at times.
The warmest temperatures measured by Spirit were 35 C in the shade for the air temperatures, and above 30 C for solar panel temperatures. Mars Exploration Rover Mission: Spotlight
You can look at Curiosity's daily readings here: Rover Environmental Monitoring Station (REMS) - Mars Science Laboratory
For instance today it varied from -77 to -13 C for the ground temperature. But depending on the time of year, it often goes above 0 C briefly at midday.
Some forms of life can survive in temperatures like this. There is life in Antarctica. They don't even need to have water, there are lichens and some cyanobacteria that the German aerospace company DLR found could metabolize and photosynthesize even without any water at all using just the night time humidity on Mars at least in short term tests of a month or so in Mars simulation chambers.
We have a lot to learn about Mars. Curiosity independently found evidence that there is a liquid layer thought to be just a centimeter or two below the sand dunes it drives over, again indirectly through the reduction in the moisture vapour content of the air, which is probably taken up by salts in the sand. They said it is not thought to be a habitat for Earth life, it gets warm enough, but at those times is too dry, and wet enough but at those times is too cold.
But it is not far off from Earth habitability regions, and Mars life of course, with different biochemistry, could potentially be able to live at lower temperatures than Earth life. And Nilton Renno commented on those results - that life in biofilms might be able to create microhabitats that can lead to habitability.
There are lots of other potential habitats on Mars. Basically the only way we can find out is to study Mars carefully close up. In such harsh conditions any life is likely to be microbial, or if it is multicellular, perhaps lichens, or some such and it seems to be low in resources for life to use, so likely to be in small numbers, and growing slowly or sporadically - at any rate unlikely to be able to find the life from orbit - or at least - prove that it is life.
I think myself that NASA are going in the wrong direction with their sample returns to find either present day or past life. Because - organics don't mean life on Mars. It gets a steady influx of organics from meteorites, and the big surprise was that Curiosity didn't find organics sooner. The organics found by Curiosity are almost certainly from meteorites - the experts say.
If life is very common on Mars, then perhaps ExoMars will find it, because it will search for biosignatures directly. If not, then we may need to search for it on Mars searching various past and present day habitats to try to find it.
When you have to search for something, and you don't know where it is, and expect it to be rare and hard to spot, and when there are organics from meteorites to confuse the search, then returning samples a few at a time from Mars to Earth doesn't seem an efficient way to find it. Surely far better to search for it in situ. This is not just me saying it, many astrobiologists have said that NASA should send in situ life detection instruments to Mars - continuing the search started by Viking.
We now have super-sensitive instruments. The life detection instruments on Viking were bulky and used lots of power, now they can be miniaturized and use hardly any power and weigh only ounces.
I think it is high time myself that we sent some capable life detection instruments to Mars.
There's a problem sterilizing our instruments sufficiently to explore the more habitable areas of Mars. But if Viking was right, then there may be life everywhere on Mars. It's potentially habitable for Earth lichens and some cyanobacteria even in equatorial regions. And - though not habitable for Earth life, at least probably not, that layer of brine just below the surface of the sand dunes may be habitable for Mars life.
Surely we should take a look and see if there is life right where our rovers are now? A null result is also significant. Most think Viking didn't detect life, while a few think it did especially after reanalysing its data, apparent detection of delayed onset circadian rhythms.
As scientists, seems like a logical place to start is to follow on from Viking, see if there is any life in the soils in the equatorial regions, test the surface, the thin layers found by Curiosity, go up to rocks and test any interesting patches, etc.
It may be unlikely, many would say, but not impossible. Anyway - though it is more designed for search for past life, ExoMars will be able to search for present day biosignatures too, and the first since Viking to be able to do that. It might give us some interesting data there.
If we don't find life almost everywhere on Mars, then the next step would be to explore the RSLs and other such places with possibly favoured habitats for life, and see if it is there - but that will require rovers cleaner than our present day ones.
We could though find more about them from orbit. CRISM is very limited, only able to do spectroscopy from orbit at 3 pm local time, and for the RSLs would be good to examine them in early hours of the day. Its resolution is only 18 meters per pixel.
The ESA Trace Gas Orbiter due for launch in 2016, will give us high resolution ultra sensitive measurements of methane and other molecules from orbit. It could detect life if it is reasonably abundant on Mars, though not if it is very rare e.g. only confined to the RSLs and a few other habitats.
http://exploration.esa.int/mars/...
See also:
Rhythms From Martian Sands - What Did Our Viking Landers Find in 1976? Astonishingly, We Don't Know
Will NASA's Sample Return Answer Mars Life Questions? Need For Comparison With In Situ Search
Places on Mars to Look for Microbes, Lichens, ...
The warmest temperatures measured by Spirit were 35 C in the shade for the air temperatures, and above 30 C for solar panel temperatures. Mars Exploration Rover Mission: Spotlight
You can look at Curiosity's daily readings here: Rover Environmental Monitoring Station (REMS) - Mars Science Laboratory
For instance today it varied from -77 to -13 C for the ground temperature. But depending on the time of year, it often goes above 0 C briefly at midday.
Some forms of life can survive in temperatures like this. There is life in Antarctica. They don't even need to have water, there are lichens and some cyanobacteria that the German aerospace company DLR found could metabolize and photosynthesize even without any water at all using just the night time humidity on Mars at least in short term tests of a month or so in Mars simulation chambers.
We have a lot to learn about Mars. Curiosity independently found evidence that there is a liquid layer thought to be just a centimeter or two below the sand dunes it drives over, again indirectly through the reduction in the moisture vapour content of the air, which is probably taken up by salts in the sand. They said it is not thought to be a habitat for Earth life, it gets warm enough, but at those times is too dry, and wet enough but at those times is too cold.
But it is not far off from Earth habitability regions, and Mars life of course, with different biochemistry, could potentially be able to live at lower temperatures than Earth life. And Nilton Renno commented on those results - that life in biofilms might be able to create microhabitats that can lead to habitability.
There are lots of other potential habitats on Mars. Basically the only way we can find out is to study Mars carefully close up. In such harsh conditions any life is likely to be microbial, or if it is multicellular, perhaps lichens, or some such and it seems to be low in resources for life to use, so likely to be in small numbers, and growing slowly or sporadically - at any rate unlikely to be able to find the life from orbit - or at least - prove that it is life.
I think myself that NASA are going in the wrong direction with their sample returns to find either present day or past life. Because - organics don't mean life on Mars. It gets a steady influx of organics from meteorites, and the big surprise was that Curiosity didn't find organics sooner. The organics found by Curiosity are almost certainly from meteorites - the experts say.
If life is very common on Mars, then perhaps ExoMars will find it, because it will search for biosignatures directly. If not, then we may need to search for it on Mars searching various past and present day habitats to try to find it.
When you have to search for something, and you don't know where it is, and expect it to be rare and hard to spot, and when there are organics from meteorites to confuse the search, then returning samples a few at a time from Mars to Earth doesn't seem an efficient way to find it. Surely far better to search for it in situ. This is not just me saying it, many astrobiologists have said that NASA should send in situ life detection instruments to Mars - continuing the search started by Viking.
We now have super-sensitive instruments. The life detection instruments on Viking were bulky and used lots of power, now they can be miniaturized and use hardly any power and weigh only ounces.
I think it is high time myself that we sent some capable life detection instruments to Mars.
There's a problem sterilizing our instruments sufficiently to explore the more habitable areas of Mars. But if Viking was right, then there may be life everywhere on Mars. It's potentially habitable for Earth lichens and some cyanobacteria even in equatorial regions. And - though not habitable for Earth life, at least probably not, that layer of brine just below the surface of the sand dunes may be habitable for Mars life.
Surely we should take a look and see if there is life right where our rovers are now? A null result is also significant. Most think Viking didn't detect life, while a few think it did especially after reanalysing its data, apparent detection of delayed onset circadian rhythms.
As scientists, seems like a logical place to start is to follow on from Viking, see if there is any life in the soils in the equatorial regions, test the surface, the thin layers found by Curiosity, go up to rocks and test any interesting patches, etc.
It may be unlikely, many would say, but not impossible. Anyway - though it is more designed for search for past life, ExoMars will be able to search for present day biosignatures too, and the first since Viking to be able to do that. It might give us some interesting data there.
If we don't find life almost everywhere on Mars, then the next step would be to explore the RSLs and other such places with possibly favoured habitats for life, and see if it is there - but that will require rovers cleaner than our present day ones.
We could though find more about them from orbit. CRISM is very limited, only able to do spectroscopy from orbit at 3 pm local time, and for the RSLs would be good to examine them in early hours of the day. Its resolution is only 18 meters per pixel.
The ESA Trace Gas Orbiter due for launch in 2016, will give us high resolution ultra sensitive measurements of methane and other molecules from orbit. It could detect life if it is reasonably abundant on Mars, though not if it is very rare e.g. only confined to the RSLs and a few other habitats.
http://exploration.esa.int/mars/...
See also:
Rhythms From Martian Sands - What Did Our Viking Landers Find in 1976? Astonishingly, We Don't Know
Will NASA's Sample Return Answer Mars Life Questions? Need For Comparison With In Situ Search
Places on Mars to Look for Microbes, Lichens, ...
About the Author
Robert Walker
Writer of articles on Mars and Space issues - Software Developer of Tune Smithy, Bounce Metronome etc.Studied at Wolfson College, Oxford
Lives in Isle of Mull
4.8m answer views110.3k this month
Top Writer2017, 2016, and 2015
Published WriterHuffPost, Slate, and 4 moreHuffPost, Slate, Forbes, Newsweek, Business Insider, and Science 2.0